Internal combustion engines which are utilized to power outboard motors are commonly oriented vertically in a cowling of the motor. In this arrangement, the pistons reciprocate along horizontal axis. Each piston is connected, via a crankrod, to a vertically extending crankshaft. This crankshaft extends out the bottom of the engine in driving relation with a water propulsion device of the outboard motor.
This outboard motor engine arrangement has the advantage that the crankshaft is oriented for simple connection to a transmission or other drive for the water propulsion device. Several disadvantages are associated with this engine arrangement, however. One problem relates to the lubricating system.
As is well known, in these engines crank-bearing halves are connected to crankshaft supports extending from the cylinder block for rotatably supporting the crankshaft. Corresponding bearing halves are supported by mating supports extending from a crankcase cover which is connected to the block. Normally, the bearing halves supported by the cover are connected to solid webs extending inwardly from a wall of the cover.
Oil is supplied by an oil pump from an oil pan to oil passages throughout the engine. These passages include a main passage and several bearing passages for lubricating the crankshaft bearing areas. It is then intended for the lubricating oil to drain through the crankcase to the bottom of the crankcase for recovery and delivery back to the oil pan.
It has been found, however, that much of the lubricating oil is thrown by the rotating crankshaft against the wall of the crankcase cover. This oil largely becomes trapped, since the bearings and their associated webs which extend inwardly from the wall of the cover prevent the movement of the oil downwardly to the bottom of the crankcase. The total amount of oil available for distribution through the engine while it is running is reduced, and the oil within the crankcase may be foamed as it is thrown from the crankshaft against the cover, runs back towards the crankshaft, and is thrown against the wall in repeating fashion.
A bearing arrangement for rotatably supporting a crankshaft of a vertically arranged engine, where a drain path is provided for the oil used to lubricating the bearings, is desired.